The present invention relates to a clamping system, a collet, a base element, a reduction sleeve and a rotating tool The present invention furthermore relates to an installation method for a clamping system.
It is known to support rotating tools like for example drills and in particular milling tools in a clamping device of a machine tool. Such clamping devices include a base element with a coupling side end for reception in a machine tool. Furthermore the base element includes a tool side end with a receiving bore hole that is concentric to a rotation axis of the rotating tool. In this receiving bore hole a shaft of the rotating tool is insertable in axial direction starting from a forward face of the tool side end of the base element.
A collet is arranged axially moveable in the receiving bore hole of the base element, wherein the collet envelops the shaft of the rotating tool. This collet preferably has a conical shape which tapers in a direction towards the coupling side end of the base element. The collet is supported at an equally tapering conical section of the radial inner surface of the receiving bore hole of the base element.
In order to attach the collet and the shaft of the rotating tool arranged therein the clamping nut axially forces the collet into the receiving bore hole of the base element in a direction of the coupling side and of the base element. When tightening the clamping nut the collet is pressed into the conical receiving bore hole of the base element so that the inner diameter of the collet is reduced and the collet is radially clamped in the receiving bore hole of the base element. Thus, the collet as well as the shaft of the rotating tool is supported in the base element in a friction locking manner.
According to another known embodiment of a clamping system the collet is a shrink fit collet which is clamped in the base element or in the chuck. In a system of this type in which the shrink fit collet is fixated in the base element through shrinking no additional clamping nut is required. Alternatively a shrink fit collet can also be interpreted as a collet which is shrunk with the tool to form an integral unit together with the rotating tool. According to another alternative clamping system the rotating tool is clamped directly in the base element or chuck and thus fixated. Respective embodiments are a shrink fit chuck and a hydro expansion chuck. In these clamping systems that include a base element or a chuck and a rotating tool neither a collet nor a clamping nut is required for attaching the rotating tool.
Due to its configurative cooperation the combination of the base element, collet and clamping nut is also designated as clamping system. A clamping system of this type is described for example in WO 2008/049 621 A2.
In the field of tool holders with clamping system for rotating tools in particular in the field of heavy duty chip removal over and over again there are problems with respect to strength of the clamping system. Heavy duty chip removal causes high forces and torques which are transferred by the rotating tool for example a cutter or drill bit through the collet supporting the rotating tool to the base element or the chuck. During heavy duty chip removal it can occur that the prevailing forces and/or torques exceed the retaining force between collet and base element. In this case the collet starts turning or slipping in the base element. This stops operations which causes undesirable production interruptions since the rotating tool has to be newly clamped. However it is also possible that the base element, the collet, the tool, the rotation machine and/or the work piece to be machined are damaged or even destroyed due to the occurring chipping forces.
Thus, it is a technical problem of the present invention to provide a clamping system for a rotating tool which reliably fixates the rotating tool and/or the collet in the base element also during heavy duty chipping operations so that the disadvantages known in the prior art are avoided.